Partitioned convolution. Various additional buffers must be supplied.
Mono impulse response only! If inputting multiple channels, you'll need independent PartConvs, one for each channel.
But the charm is: impulse response can be as large as you like (CPU load increases with IR size. Various tradeoffs based on fftsize choice, due to rarer but larger FFTs. This plug-in uses amortisation to spread processing and avoid spikes).
Normalisation factors difficult to anticipate; convolution piles up multiple copies of the input on top of itself, so can easily overload.
| in |
processing target. |
| fftsize |
spectral convolution partition size (twice partition size). You must ensure that the blocksize divides the partition size and there are at least two blocks per partition (to allow for amortisation). |
| irbufnum |
prepared buffer of spectra for each partition of the inpulse response. |
| mul | |
| add |
// preparation; essentially, allocate an impulse response buffer, then// follow a special buffer preparation step to set up the data the plugin needs.// Different options are provided commented out for loading impulse responses from soundfiles.( // also 4096 works on my machine; 1024 too often and amortisation too pushed, 8192 more high load FFT~fftsize = 2048;s.waitForBoot { { var ir, irbuffer, bufsize; // // MONO ONLY // pre-existing impulse response sound files // (could also use any general soundfile too for cross-synthesis effects) // irbuffer = Buffer.read(s, "/Volumes/data/audio/ir/ir2.wav"); // synthesise the honourable 'Dan Stowell' impulse response ir = [1] ++ 0.dup(100) ++ ( (1, 0.99998 .. 0) .collect {|f| f = f.squared.squared; f = if(f.coin) { 0 }{ f.squared }; f = if(0.5.coin) { 0 - f } { f } } * 0.1 ); ir = ir.normalizeSum; irbuffer = Buffer.loadCollection(s, ir); s.sync; bufsize = PartConv.calcBufSize(~fftsize, irbuffer); // ~numpartitions= PartConv.calcNumPartitions(~fftsize, irbuffer); ~irspectrum = Buffer.alloc(s, bufsize, 1); ~irspectrum.preparePartConv(irbuffer, ~fftsize); s.sync; irbuffer.free; // don't need time domain data anymore, just needed spectral version }.fork;})~target = Buffer.read(s, Platform.resourceDir +/+ "sounds/a11wlk01.wav");({ var input = PlayBuf.ar(1, ~target, loop:1); PartConv.ar(input, ~fftsize, ~irspectrum.bufnum, 0.5)}.play)// convolve with live input({ var input = SoundIn.ar(0); PartConv.ar(input, ~fftsize, ~irspectrum.bufnum)}.play)// should get back original impulse response (once every four seconds)({ var input = Impulse.ar(0.25); PartConv.ar(input, ~fftsize, ~irspectrum.bufnum)}.play)// only free buffers once you're finished with examples// if you free whilst PartConv is still running, the server won't crash, but PartConv output will go to zero abruptly(~irspectrum.free;~target.free;currentEnvironment.clear;)